/**
 * @file
 * Sequential API External module
 *
 * @defgroup netconn Netconn API
 * @ingroup sequential_api
 * Thread-safe, to be called from non-TCPIP threads only.
 * TX/RX handling based on @ref netbuf (containing @ref pbuf)
 * to avoid copying data around.
 *
 * @defgroup netconn_common Common functions
 * @ingroup netconn
 * For use with TCP and UDP
 *
 * @defgroup netconn_tcp TCP only
 * @ingroup netconn
 * TCP only functions
 *
 * @defgroup netconn_udp UDP only
 * @ingroup netconn
 * UDP only functions
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 */

/* This is the part of the API that is linked with
   the application */

#include "lwip/opt.h"

#if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */

#include "lwip/api.h"
#include "lwip/memp.h"

#include "lwip/ip.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/priv/api_msg.h"
#include "lwip/priv/tcp_priv.h"
#include "lwip/priv/tcpip_priv.h"

#include <string.h>

#define API_MSG_VAR_REF(name)               API_VAR_REF(name)
#define API_MSG_VAR_DECLARE(name)           API_VAR_DECLARE(struct api_msg, name)
#define API_MSG_VAR_ALLOC(name)             API_VAR_ALLOC(struct api_msg, MEMP_API_MSG, name, ERR_MEM)
#define API_MSG_VAR_ALLOC_RETURN_NULL(name) API_VAR_ALLOC(struct api_msg, MEMP_API_MSG, name, NULL)
#define API_MSG_VAR_FREE(name)              API_VAR_FREE(MEMP_API_MSG, name)

static err_t netconn_close_shutdown(struct netconn* conn, u8_t how);

/**
 * Call the lower part of a netconn_* function
 * This function is then running in the thread context
 * of tcpip_thread and has exclusive access to lwIP core code.
 *
 * @param fn function to call
 * @param apimsg a struct containing the function to call and its parameters
 * @return ERR_OK if the function was called, another err_t if not
 */
static err_t
netconn_apimsg(tcpip_callback_fn fn, struct api_msg* apimsg)
{
	err_t err;

#ifdef LWIP_DEBUG
	/* catch functions that don't set err */
	apimsg->err = ERR_VAL;
#endif /* LWIP_DEBUG */

#if LWIP_NETCONN_SEM_PER_THREAD
	apimsg->op_completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
#endif /* LWIP_NETCONN_SEM_PER_THREAD */

	err = tcpip_send_msg_wait_sem(fn, apimsg, LWIP_API_MSG_SEM(apimsg));

	if(err == ERR_OK) {
		return apimsg->err;
	}

	return err;
}

/**
 * Create a new netconn (of a specific type) that has a callback function.
 * The corresponding pcb is also created.
 *
 * @param t the type of 'connection' to create (@see enum netconn_type)
 * @param proto the IP protocol for RAW IP pcbs
 * @param callback a function to call on status changes (RX available, TX'ed)
 * @return a newly allocated struct netconn or
 *         NULL on memory error
 */
struct netconn*
netconn_new_with_proto_and_callback(enum netconn_type t, u8_t proto, netconn_callback callback)
{
	struct netconn* conn;
	API_MSG_VAR_DECLARE(msg);
	API_MSG_VAR_ALLOC_RETURN_NULL(msg);

	conn = netconn_alloc(t, callback);

	if(conn != NULL) {
		err_t err;

		API_MSG_VAR_REF(msg).msg.n.proto = proto;
		API_MSG_VAR_REF(msg).conn = conn;
		err = netconn_apimsg(lwip_netconn_do_newconn, &API_MSG_VAR_REF(msg));

		if(err != ERR_OK) {
			LWIP_ASSERT("freeing conn without freeing pcb", conn->pcb.tcp == NULL);
			LWIP_ASSERT("conn has no recvmbox", sys_mbox_valid(&conn->recvmbox));
#if LWIP_TCP
			LWIP_ASSERT("conn->acceptmbox shouldn't exist", !sys_mbox_valid(&conn->acceptmbox));
#endif /* LWIP_TCP */
#if !LWIP_NETCONN_SEM_PER_THREAD
			LWIP_ASSERT("conn has no op_completed", sys_sem_valid(&conn->op_completed));
			sys_sem_free(&conn->op_completed);
#endif /* !LWIP_NETCONN_SEM_PER_THREAD */
			sys_mbox_free(&conn->recvmbox);
			memp_free(MEMP_NETCONN, conn);
			API_MSG_VAR_FREE(msg);
			return NULL;
		}
	}

	API_MSG_VAR_FREE(msg);
	return conn;
}

/**
 * @ingroup netconn_common
 * Close a netconn 'connection' and free its resources.
 * UDP and RAW connection are completely closed, TCP pcbs might still be in a waitstate
 * after this returns.
 *
 * @param conn the netconn to delete
 * @return ERR_OK if the connection was deleted
 */
err_t
netconn_delete(struct netconn* conn)
{
	err_t err;
	API_MSG_VAR_DECLARE(msg);

	/* No ASSERT here because possible to get a (conn == NULL) if we got an accept error */
	if(conn == NULL) {
		return ERR_OK;
	}

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
#if LWIP_SO_SNDTIMEO || LWIP_SO_LINGER
	/* get the time we started, which is later compared to
	   sys_now() + conn->send_timeout */
	API_MSG_VAR_REF(msg).msg.sd.time_started = sys_now();
#else /* LWIP_SO_SNDTIMEO || LWIP_SO_LINGER */
#if LWIP_TCP
	API_MSG_VAR_REF(msg).msg.sd.polls_left =
	    ((LWIP_TCP_CLOSE_TIMEOUT_MS_DEFAULT + TCP_SLOW_INTERVAL - 1) / TCP_SLOW_INTERVAL) + 1;
#endif /* LWIP_TCP */
#endif /* LWIP_SO_SNDTIMEO || LWIP_SO_LINGER */
	err = netconn_apimsg(lwip_netconn_do_delconn, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	if(err != ERR_OK) {
		return err;
	}

	netconn_free(conn);

	return ERR_OK;
}

/**
 * Get the local or remote IP address and port of a netconn.
 * For RAW netconns, this returns the protocol instead of a port!
 *
 * @param conn the netconn to query
 * @param addr a pointer to which to save the IP address
 * @param port a pointer to which to save the port (or protocol for RAW)
 * @param local 1 to get the local IP address, 0 to get the remote one
 * @return ERR_CONN for invalid connections
 *         ERR_OK if the information was retrieved
 */
err_t
netconn_getaddr(struct netconn* conn, ip_addr_t* addr, u16_t* port, u8_t local)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	LWIP_ERROR("netconn_getaddr: invalid conn", (conn != NULL), return ERR_ARG;);
	LWIP_ERROR("netconn_getaddr: invalid addr", (addr != NULL), return ERR_ARG;);
	LWIP_ERROR("netconn_getaddr: invalid port", (port != NULL), return ERR_ARG;);

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
	API_MSG_VAR_REF(msg).msg.ad.local = local;
#if LWIP_MPU_COMPATIBLE
	err = netconn_apimsg(lwip_netconn_do_getaddr, &API_MSG_VAR_REF(msg));
	*addr = msg->msg.ad.ipaddr;
	*port = msg->msg.ad.port;
#else /* LWIP_MPU_COMPATIBLE */
	msg.msg.ad.ipaddr = addr;
	msg.msg.ad.port = port;
	err = netconn_apimsg(lwip_netconn_do_getaddr, &msg);
#endif /* LWIP_MPU_COMPATIBLE */
	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_common
 * Bind a netconn to a specific local IP address and port.
 * Binding one netconn twice might not always be checked correctly!
 *
 * @param conn the netconn to bind
 * @param addr the local IP address to bind the netconn to
 *             (use IP4_ADDR_ANY/IP6_ADDR_ANY to bind to all addresses)
 * @param port the local port to bind the netconn to (not used for RAW)
 * @return ERR_OK if bound, any other err_t on failure
 */
err_t
netconn_bind(struct netconn* conn, const ip_addr_t* addr, u16_t port)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	LWIP_ERROR("netconn_bind: invalid conn", (conn != NULL), return ERR_ARG;);

#if LWIP_IPV4

	/* Don't propagate NULL pointer (IP_ADDR_ANY alias) to subsequent functions */
	if(addr == NULL) {
		addr = IP4_ADDR_ANY;
	}

#endif /* LWIP_IPV4 */

#if LWIP_IPV4 && LWIP_IPV6

	/* "Socket API like" dual-stack support: If IP to bind to is IP6_ADDR_ANY,
	 * and NETCONN_FLAG_IPV6_V6ONLY is 0, use IP_ANY_TYPE to bind
	 */
	if((netconn_get_ipv6only(conn) == 0) &&
	        ip_addr_cmp(addr, IP6_ADDR_ANY)) {
		addr = IP_ANY_TYPE;
	}

#endif /* LWIP_IPV4 && LWIP_IPV6 */

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
	API_MSG_VAR_REF(msg).msg.bc.ipaddr = API_MSG_VAR_REF(addr);
	API_MSG_VAR_REF(msg).msg.bc.port = port;
	err = netconn_apimsg(lwip_netconn_do_bind, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_common
 * Connect a netconn to a specific remote IP address and port.
 *
 * @param conn the netconn to connect
 * @param addr the remote IP address to connect to
 * @param port the remote port to connect to (no used for RAW)
 * @return ERR_OK if connected, return value of tcp_/udp_/raw_connect otherwise
 */
err_t
netconn_connect(struct netconn* conn, const ip_addr_t* addr, u16_t port)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	LWIP_ERROR("netconn_connect: invalid conn", (conn != NULL), return ERR_ARG;);

#if LWIP_IPV4

	/* Don't propagate NULL pointer (IP_ADDR_ANY alias) to subsequent functions */
	if(addr == NULL) {
		addr = IP4_ADDR_ANY;
	}

#endif /* LWIP_IPV4 */

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
	API_MSG_VAR_REF(msg).msg.bc.ipaddr = API_MSG_VAR_REF(addr);
	API_MSG_VAR_REF(msg).msg.bc.port = port;
	err = netconn_apimsg(lwip_netconn_do_connect, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_udp
 * Disconnect a netconn from its current peer (only valid for UDP netconns).
 *
 * @param conn the netconn to disconnect
 * @return See @ref err_t
 */
err_t
netconn_disconnect(struct netconn* conn)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	LWIP_ERROR("netconn_disconnect: invalid conn", (conn != NULL), return ERR_ARG;);

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
	err = netconn_apimsg(lwip_netconn_do_disconnect, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_tcp
 * Set a TCP netconn into listen mode
 *
 * @param conn the tcp netconn to set to listen mode
 * @param backlog the listen backlog, only used if TCP_LISTEN_BACKLOG==1
 * @return ERR_OK if the netconn was set to listen (UDP and RAW netconns
 *         don't return any error (yet?))
 */
err_t
netconn_listen_with_backlog(struct netconn* conn, u8_t backlog)
{
#if LWIP_TCP
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	/* This does no harm. If TCP_LISTEN_BACKLOG is off, backlog is unused. */
	LWIP_UNUSED_ARG(backlog);

	LWIP_ERROR("netconn_listen: invalid conn", (conn != NULL), return ERR_ARG;);

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
#if TCP_LISTEN_BACKLOG
	API_MSG_VAR_REF(msg).msg.lb.backlog = backlog;
#endif /* TCP_LISTEN_BACKLOG */
	err = netconn_apimsg(lwip_netconn_do_listen, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
#else /* LWIP_TCP */
	LWIP_UNUSED_ARG(conn);
	LWIP_UNUSED_ARG(backlog);
	return ERR_ARG;
#endif /* LWIP_TCP */
}

/**
 * @ingroup netconn_tcp
 * Accept a new connection on a TCP listening netconn.
 *
 * @param conn the TCP listen netconn
 * @param new_conn pointer where the new connection is stored
 * @return ERR_OK if a new connection has been received or an error
 *                code otherwise
 */
err_t
netconn_accept(struct netconn* conn, struct netconn** new_conn)
{
#if LWIP_TCP
	void* accept_ptr;
	struct netconn* newconn;
#if TCP_LISTEN_BACKLOG
	API_MSG_VAR_DECLARE(msg);
#endif /* TCP_LISTEN_BACKLOG */

	LWIP_ERROR("netconn_accept: invalid pointer", (new_conn != NULL),                  return ERR_ARG;);
	*new_conn = NULL;
	LWIP_ERROR("netconn_accept: invalid conn", (conn != NULL),                      return ERR_ARG;);

	if(ERR_IS_FATAL(conn->last_err)) {
		/* don't recv on fatal errors: this might block the application task
		   waiting on acceptmbox forever! */
		return conn->last_err;
	}

	if(!sys_mbox_valid(&conn->acceptmbox)) {
		return ERR_CLSD;
	}

#if TCP_LISTEN_BACKLOG
	API_MSG_VAR_ALLOC(msg);
#endif /* TCP_LISTEN_BACKLOG */

#if LWIP_SO_RCVTIMEO

	if(sys_arch_mbox_fetch(&conn->acceptmbox, &accept_ptr, conn->recv_timeout) == SYS_ARCH_TIMEOUT) {
#if TCP_LISTEN_BACKLOG
		API_MSG_VAR_FREE(msg);
#endif /* TCP_LISTEN_BACKLOG */
		return ERR_TIMEOUT;
	}

#else
	sys_arch_mbox_fetch(&conn->acceptmbox, &accept_ptr, 0);
#endif /* LWIP_SO_RCVTIMEO*/
	newconn = (struct netconn*)accept_ptr;
	/* Register event with callback */
	API_EVENT(conn, NETCONN_EVT_RCVMINUS, 0);

	if(accept_ptr == &netconn_aborted) {
		/* a connection has been aborted: out of pcbs or out of netconns during accept */
		/* @todo: set netconn error, but this would be fatal and thus block further accepts */
#if TCP_LISTEN_BACKLOG
		API_MSG_VAR_FREE(msg);
#endif /* TCP_LISTEN_BACKLOG */
		return ERR_ABRT;
	}

	if(newconn == NULL) {
		/* connection has been aborted */
		/* in this special case, we set the netconn error from application thread, as
		   on a ready-to-accept listening netconn, there should not be anything running
		   in tcpip_thread */
		NETCONN_SET_SAFE_ERR(conn, ERR_CLSD);
#if TCP_LISTEN_BACKLOG
		API_MSG_VAR_FREE(msg);
#endif /* TCP_LISTEN_BACKLOG */
		return ERR_CLSD;
	}

#if TCP_LISTEN_BACKLOG
	/* Let the stack know that we have accepted the connection. */
	API_MSG_VAR_REF(msg).conn = newconn;
	/* don't care for the return value of lwip_netconn_do_recv */
	netconn_apimsg(lwip_netconn_do_accepted, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);
#endif /* TCP_LISTEN_BACKLOG */

	*new_conn = newconn;
	/* don't set conn->last_err: it's only ERR_OK, anyway */
	return ERR_OK;
#else /* LWIP_TCP */
	LWIP_UNUSED_ARG(conn);
	LWIP_UNUSED_ARG(new_conn);
	return ERR_ARG;
#endif /* LWIP_TCP */
}

/**
 * @ingroup netconn_common
 * Receive data: actual implementation that doesn't care whether pbuf or netbuf
 * is received
 *
 * @param conn the netconn from which to receive data
 * @param new_buf pointer where a new pbuf/netbuf is stored when received data
 * @return ERR_OK if data has been received, an error code otherwise (timeout,
 *                memory error or another error)
 */
static err_t
netconn_recv_data(struct netconn* conn, void** new_buf)
{
	void* buf = NULL;
	u16_t len;
#if LWIP_TCP
	API_MSG_VAR_DECLARE(msg);
#if LWIP_MPU_COMPATIBLE
	msg = NULL;
#endif
#endif /* LWIP_TCP */

	LWIP_ERROR("netconn_recv: invalid pointer", (new_buf != NULL), return ERR_ARG;);
	*new_buf = NULL;
	LWIP_ERROR("netconn_recv: invalid conn", (conn != NULL),    return ERR_ARG;);
#if LWIP_TCP
#if (LWIP_UDP || LWIP_RAW)

	if(NETCONNTYPE_GROUP(conn->type) == NETCONN_TCP)
#endif /* (LWIP_UDP || LWIP_RAW) */
	{
		if(!sys_mbox_valid(&conn->recvmbox)) {
			/* This happens when calling this function after receiving FIN */
			return sys_mbox_valid(&conn->acceptmbox) ? ERR_CONN : ERR_CLSD;
		}
	}

#endif /* LWIP_TCP */
	LWIP_ERROR("netconn_recv: invalid recvmbox", sys_mbox_valid(&conn->recvmbox), return ERR_CONN;);

	if(ERR_IS_FATAL(conn->last_err)) {
		/* don't recv on fatal errors: this might block the application task
		   waiting on recvmbox forever! */
		/* @todo: this does not allow us to fetch data that has been put into recvmbox
		   before the fatal error occurred - is that a problem? */
		return conn->last_err;
	}

#if LWIP_TCP
#if (LWIP_UDP || LWIP_RAW)

	if(NETCONNTYPE_GROUP(conn->type) == NETCONN_TCP)
#endif /* (LWIP_UDP || LWIP_RAW) */
	{
		API_MSG_VAR_ALLOC(msg);
	}

#endif /* LWIP_TCP */

#if LWIP_SO_RCVTIMEO

	if(sys_arch_mbox_fetch(&conn->recvmbox, &buf, conn->recv_timeout) == SYS_ARCH_TIMEOUT) {
#if LWIP_TCP
#if (LWIP_UDP || LWIP_RAW)

		if(NETCONNTYPE_GROUP(conn->type) == NETCONN_TCP)
#endif /* (LWIP_UDP || LWIP_RAW) */
		{
			API_MSG_VAR_FREE(msg);
		}

#endif /* LWIP_TCP */
		return ERR_TIMEOUT;
	}

#else
	sys_arch_mbox_fetch(&conn->recvmbox, &buf, 0);
#endif /* LWIP_SO_RCVTIMEO*/

#if LWIP_TCP
#if (LWIP_UDP || LWIP_RAW)

	if(NETCONNTYPE_GROUP(conn->type) == NETCONN_TCP)
#endif /* (LWIP_UDP || LWIP_RAW) */
	{
		/* Let the stack know that we have taken the data. */
		/* @todo: Speedup: Don't block and wait for the answer here
		   (to prevent multiple thread-switches). */
		API_MSG_VAR_REF(msg).conn = conn;

		if(buf != NULL) {
			API_MSG_VAR_REF(msg).msg.r.len = ((struct pbuf*)buf)->tot_len;
		} else {
			API_MSG_VAR_REF(msg).msg.r.len = 1;
		}

		/* don't care for the return value of lwip_netconn_do_recv */
		netconn_apimsg(lwip_netconn_do_recv, &API_MSG_VAR_REF(msg));
		API_MSG_VAR_FREE(msg);

		/* If we are closed, we indicate that we no longer wish to use the socket */
		if(buf == NULL) {
			API_EVENT(conn, NETCONN_EVT_RCVMINUS, 0);

			if(conn->pcb.ip == NULL) {
				/* race condition: RST during recv */
				return conn->last_err == ERR_OK ? ERR_RST : conn->last_err;
			}

			/* RX side is closed, so deallocate the recvmbox */
			netconn_close_shutdown(conn, NETCONN_SHUT_RD);
			/* Don' store ERR_CLSD as conn->err since we are only half-closed */
			return ERR_CLSD;
		}

		len = ((struct pbuf*)buf)->tot_len;
	}

#endif /* LWIP_TCP */
#if LWIP_TCP && (LWIP_UDP || LWIP_RAW)
	else
#endif /* LWIP_TCP && (LWIP_UDP || LWIP_RAW) */
#if (LWIP_UDP || LWIP_RAW)
	{
		LWIP_ASSERT("buf != NULL", buf != NULL);
		len = netbuf_len((struct netbuf*)buf);
	}

#endif /* (LWIP_UDP || LWIP_RAW) */

#if LWIP_SO_RCVBUF
	SYS_ARCH_DEC(conn->recv_avail, len);
#endif /* LWIP_SO_RCVBUF */
	/* Register event with callback */
	API_EVENT(conn, NETCONN_EVT_RCVMINUS, len);

	LWIP_DEBUGF(API_LIB_DEBUG, ("netconn_recv_data: received %p, len=%"U16_F"\n", buf, len));

	*new_buf = buf;
	/* don't set conn->last_err: it's only ERR_OK, anyway */
	return ERR_OK;
}

/**
 * @ingroup netconn_tcp
 * Receive data (in form of a pbuf) from a TCP netconn
 *
 * @param conn the netconn from which to receive data
 * @param new_buf pointer where a new pbuf is stored when received data
 * @return ERR_OK if data has been received, an error code otherwise (timeout,
 *                memory error or another error)
 *         ERR_ARG if conn is not a TCP netconn
 */
err_t
netconn_recv_tcp_pbuf(struct netconn* conn, struct pbuf** new_buf)
{
	LWIP_ERROR("netconn_recv: invalid conn", (conn != NULL) &&
	           NETCONNTYPE_GROUP(netconn_type(conn)) == NETCONN_TCP, return ERR_ARG;);

	return netconn_recv_data(conn, (void**)new_buf);
}

/**
 * @ingroup netconn_common
 * Receive data (in form of a netbuf containing a packet buffer) from a netconn
 *
 * @param conn the netconn from which to receive data
 * @param new_buf pointer where a new netbuf is stored when received data
 * @return ERR_OK if data has been received, an error code otherwise (timeout,
 *                memory error or another error)
 */
err_t
netconn_recv(struct netconn* conn, struct netbuf** new_buf)
{
#if LWIP_TCP
	struct netbuf* buf = NULL;
	err_t err;
#endif /* LWIP_TCP */

	LWIP_ERROR("netconn_recv: invalid pointer", (new_buf != NULL), return ERR_ARG;);
	*new_buf = NULL;
	LWIP_ERROR("netconn_recv: invalid conn", (conn != NULL),    return ERR_ARG;);

#if LWIP_TCP
#if (LWIP_UDP || LWIP_RAW)

	if(NETCONNTYPE_GROUP(conn->type) == NETCONN_TCP)
#endif /* (LWIP_UDP || LWIP_RAW) */
	{
		struct pbuf* p = NULL;
		/* This is not a listening netconn, since recvmbox is set */

		buf = (struct netbuf*)memp_malloc(MEMP_NETBUF);

		if(buf == NULL) {
			return ERR_MEM;
		}

		err = netconn_recv_data(conn, (void**)&p);

		if(err != ERR_OK) {
			memp_free(MEMP_NETBUF, buf);
			return err;
		}

		LWIP_ASSERT("p != NULL", p != NULL);

		buf->p = p;
		buf->ptr = p;
		buf->port = 0;
		ip_addr_set_zero(&buf->addr);
		*new_buf = buf;
		/* don't set conn->last_err: it's only ERR_OK, anyway */
		return ERR_OK;
	}

#endif /* LWIP_TCP */
#if LWIP_TCP && (LWIP_UDP || LWIP_RAW)
	else
#endif /* LWIP_TCP && (LWIP_UDP || LWIP_RAW) */
	{
#if (LWIP_UDP || LWIP_RAW)
		return netconn_recv_data(conn, (void**)new_buf);
#endif /* (LWIP_UDP || LWIP_RAW) */
	}
}

/**
 * @ingroup netconn_udp
 * Send data (in form of a netbuf) to a specific remote IP address and port.
 * Only to be used for UDP and RAW netconns (not TCP).
 *
 * @param conn the netconn over which to send data
 * @param buf a netbuf containing the data to send
 * @param addr the remote IP address to which to send the data
 * @param port the remote port to which to send the data
 * @return ERR_OK if data was sent, any other err_t on error
 */
err_t
netconn_sendto(struct netconn* conn, struct netbuf* buf, const ip_addr_t* addr, u16_t port)
{
	if(buf != NULL) {
		ip_addr_set(&buf->addr, addr);
		buf->port = port;
		return netconn_send(conn, buf);
	}

	return ERR_VAL;
}

/**
 * @ingroup netconn_udp
 * Send data over a UDP or RAW netconn (that is already connected).
 *
 * @param conn the UDP or RAW netconn over which to send data
 * @param buf a netbuf containing the data to send
 * @return ERR_OK if data was sent, any other err_t on error
 */
err_t
netconn_send(struct netconn* conn, struct netbuf* buf)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	LWIP_ERROR("netconn_send: invalid conn", (conn != NULL), return ERR_ARG;);

	LWIP_DEBUGF(API_LIB_DEBUG, ("netconn_send: sending %"U16_F" bytes\n", buf->p->tot_len));

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
	API_MSG_VAR_REF(msg).msg.b = buf;
	err = netconn_apimsg(lwip_netconn_do_send, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_tcp
 * Send data over a TCP netconn.
 *
 * @param conn the TCP netconn over which to send data
 * @param dataptr pointer to the application buffer that contains the data to send
 * @param size size of the application data to send
 * @param apiflags combination of following flags :
 * - NETCONN_COPY: data will be copied into memory belonging to the stack
 * - NETCONN_MORE: for TCP connection, PSH flag will be set on last segment sent
 * - NETCONN_DONTBLOCK: only write the data if all data can be written at once
 * @param bytes_written pointer to a location that receives the number of written bytes
 * @return ERR_OK if data was sent, any other err_t on error
 */
err_t
netconn_write_partly(struct netconn* conn, const void* dataptr, size_t size,
                     u8_t apiflags, size_t* bytes_written)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;
	u8_t dontblock;

	LWIP_ERROR("netconn_write: invalid conn", (conn != NULL), return ERR_ARG;);
	LWIP_ERROR("netconn_write: invalid conn->type", (NETCONNTYPE_GROUP(conn->type) == NETCONN_TCP), return ERR_VAL;);

	if(size == 0) {
		return ERR_OK;
	}

	dontblock = netconn_is_nonblocking(conn) || (apiflags & NETCONN_DONTBLOCK);
#if LWIP_SO_SNDTIMEO

	if(conn->send_timeout != 0) {
		dontblock = 1;
	}

#endif /* LWIP_SO_SNDTIMEO */

	if(dontblock && !bytes_written) {
		/* This implies netconn_write() cannot be used for non-blocking send, since
		   it has no way to return the number of bytes written. */
		return ERR_VAL;
	}

	API_MSG_VAR_ALLOC(msg);
	/* non-blocking write sends as much  */
	API_MSG_VAR_REF(msg).conn = conn;
	API_MSG_VAR_REF(msg).msg.w.dataptr = dataptr;
	API_MSG_VAR_REF(msg).msg.w.apiflags = apiflags;
	API_MSG_VAR_REF(msg).msg.w.len = size;
#if LWIP_SO_SNDTIMEO

	if(conn->send_timeout != 0) {
		/* get the time we started, which is later compared to
		    sys_now() + conn->send_timeout */
		API_MSG_VAR_REF(msg).msg.w.time_started = sys_now();
	} else {
		API_MSG_VAR_REF(msg).msg.w.time_started = 0;
	}

#endif /* LWIP_SO_SNDTIMEO */

	/* For locking the core: this _can_ be delayed on low memory/low send buffer,
	   but if it is, this is done inside api_msg.c:do_write(), so we can use the
	   non-blocking version here. */
	err = netconn_apimsg(lwip_netconn_do_write, &API_MSG_VAR_REF(msg));

	if((err == ERR_OK) && (bytes_written != NULL)) {
		if(dontblock) {
			/* nonblocking write: maybe the data has been sent partly */
			*bytes_written = API_MSG_VAR_REF(msg).msg.w.len;
		} else {
			/* blocking call succeeded: all data has been sent if it */
			*bytes_written = size;
		}
	}

	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_tcp
 * Close or shutdown a TCP netconn (doesn't delete it).
 *
 * @param conn the TCP netconn to close or shutdown
 * @param how fully close or only shutdown one side?
 * @return ERR_OK if the netconn was closed, any other err_t on error
 */
static err_t
netconn_close_shutdown(struct netconn* conn, u8_t how)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;
	LWIP_UNUSED_ARG(how);

	LWIP_ERROR("netconn_close: invalid conn", (conn != NULL), return ERR_ARG;);

	API_MSG_VAR_ALLOC(msg);
	API_MSG_VAR_REF(msg).conn = conn;
#if LWIP_TCP
	/* shutting down both ends is the same as closing */
	API_MSG_VAR_REF(msg).msg.sd.shut = how;
#if LWIP_SO_SNDTIMEO || LWIP_SO_LINGER
	/* get the time we started, which is later compared to
	   sys_now() + conn->send_timeout */
	API_MSG_VAR_REF(msg).msg.sd.time_started = sys_now();
#else /* LWIP_SO_SNDTIMEO || LWIP_SO_LINGER */
	API_MSG_VAR_REF(msg).msg.sd.polls_left =
	    ((LWIP_TCP_CLOSE_TIMEOUT_MS_DEFAULT + TCP_SLOW_INTERVAL - 1) / TCP_SLOW_INTERVAL) + 1;
#endif /* LWIP_SO_SNDTIMEO || LWIP_SO_LINGER */
#endif /* LWIP_TCP */
	err = netconn_apimsg(lwip_netconn_do_close, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
}

/**
 * @ingroup netconn_tcp
 * Close a TCP netconn (doesn't delete it).
 *
 * @param conn the TCP netconn to close
 * @return ERR_OK if the netconn was closed, any other err_t on error
 */
err_t
netconn_close(struct netconn* conn)
{
	/* shutting down both ends is the same as closing */
	return netconn_close_shutdown(conn, NETCONN_SHUT_RDWR);
}

/**
 * @ingroup netconn_tcp
 * Shut down one or both sides of a TCP netconn (doesn't delete it).
 *
 * @param conn the TCP netconn to shut down
 * @param shut_rx shut down the RX side (no more read possible after this)
 * @param shut_tx shut down the TX side (no more write possible after this)
 * @return ERR_OK if the netconn was closed, any other err_t on error
 */
err_t
netconn_shutdown(struct netconn* conn, u8_t shut_rx, u8_t shut_tx)
{
	return netconn_close_shutdown(conn, (shut_rx ? NETCONN_SHUT_RD : 0) | (shut_tx ? NETCONN_SHUT_WR : 0));
}

#if LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD)
/**
 * @ingroup netconn_udp
 * Join multicast groups for UDP netconns.
 *
 * @param conn the UDP netconn for which to change multicast addresses
 * @param multiaddr IP address of the multicast group to join or leave
 * @param netif_addr the IP address of the network interface on which to send
 *                  the igmp message
 * @param join_or_leave flag whether to send a join- or leave-message
 * @return ERR_OK if the action was taken, any err_t on error
 */
err_t
netconn_join_leave_group(struct netconn* conn,
                         const ip_addr_t* multiaddr,
                         const ip_addr_t* netif_addr,
                         enum netconn_igmp join_or_leave)
{
	API_MSG_VAR_DECLARE(msg);
	err_t err;

	LWIP_ERROR("netconn_join_leave_group: invalid conn", (conn != NULL), return ERR_ARG;);

	API_MSG_VAR_ALLOC(msg);

#if LWIP_IPV4

	/* Don't propagate NULL pointer (IP_ADDR_ANY alias) to subsequent functions */
	if(multiaddr == NULL) {
		multiaddr = IP4_ADDR_ANY;
	}

	if(netif_addr == NULL) {
		netif_addr = IP4_ADDR_ANY;
	}

#endif /* LWIP_IPV4 */

	API_MSG_VAR_REF(msg).conn = conn;
	API_MSG_VAR_REF(msg).msg.jl.multiaddr = API_MSG_VAR_REF(multiaddr);
	API_MSG_VAR_REF(msg).msg.jl.netif_addr = API_MSG_VAR_REF(netif_addr);
	API_MSG_VAR_REF(msg).msg.jl.join_or_leave = join_or_leave;
	err = netconn_apimsg(lwip_netconn_do_join_leave_group, &API_MSG_VAR_REF(msg));
	API_MSG_VAR_FREE(msg);

	return err;
}
#endif /* LWIP_IGMP || (LWIP_IPV6 && LWIP_IPV6_MLD) */

#if LWIP_DNS
/**
 * @ingroup netconn_common
 * Execute a DNS query, only one IP address is returned
 *
 * @param name a string representation of the DNS host name to query
 * @param addr a preallocated ip_addr_t where to store the resolved IP address
 * @param dns_addrtype IP address type (IPv4 / IPv6)
 * @return ERR_OK: resolving succeeded
 *         ERR_MEM: memory error, try again later
 *         ERR_ARG: dns client not initialized or invalid hostname
 *         ERR_VAL: dns server response was invalid
 */
#if LWIP_IPV4 && LWIP_IPV6
	err_t
	netconn_gethostbyname_addrtype(const char* name, ip_addr_t* addr, u8_t dns_addrtype)
#else
	err_t
	netconn_gethostbyname(const char* name, ip_addr_t* addr)
#endif
{
	API_VAR_DECLARE(struct dns_api_msg, msg);
#if !LWIP_MPU_COMPATIBLE
	sys_sem_t sem;
#endif /* LWIP_MPU_COMPATIBLE */
	err_t err;
	err_t cberr;

	LWIP_ERROR("netconn_gethostbyname: invalid name", (name != NULL), return ERR_ARG;);
	LWIP_ERROR("netconn_gethostbyname: invalid addr", (addr != NULL), return ERR_ARG;);
#if LWIP_MPU_COMPATIBLE

	if(strlen(name) >= DNS_MAX_NAME_LENGTH) {
		return ERR_ARG;
	}

#endif

	API_VAR_ALLOC(struct dns_api_msg, MEMP_DNS_API_MSG, msg, ERR_MEM);
#if LWIP_MPU_COMPATIBLE
	strncpy(API_VAR_REF(msg).name, name, DNS_MAX_NAME_LENGTH - 1);
	API_VAR_REF(msg).name[DNS_MAX_NAME_LENGTH - 1] = 0;
#else /* LWIP_MPU_COMPATIBLE */
	msg.err = &err;
	msg.sem = &sem;
	API_VAR_REF(msg).addr = API_VAR_REF(addr);
	API_VAR_REF(msg).name = name;
#endif /* LWIP_MPU_COMPATIBLE */
#if LWIP_IPV4 && LWIP_IPV6
	API_VAR_REF(msg).dns_addrtype = dns_addrtype;
#endif /* LWIP_IPV4 && LWIP_IPV6 */
#if LWIP_NETCONN_SEM_PER_THREAD
	API_VAR_REF(msg).sem = LWIP_NETCONN_THREAD_SEM_GET();
#else /* LWIP_NETCONN_SEM_PER_THREAD*/
	err = sys_sem_new(API_EXPR_REF(API_VAR_REF(msg).sem), 0);

	if(err != ERR_OK) {
		API_VAR_FREE(MEMP_DNS_API_MSG, msg);
		return err;
	}

#endif /* LWIP_NETCONN_SEM_PER_THREAD */

	cberr = tcpip_callback(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg));

	if(cberr != ERR_OK) {
#if !LWIP_NETCONN_SEM_PER_THREAD
		sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
#endif /* !LWIP_NETCONN_SEM_PER_THREAD */
		API_VAR_FREE(MEMP_DNS_API_MSG, msg);
		return cberr;
	}

	sys_sem_wait(API_EXPR_REF_SEM(API_VAR_REF(msg).sem));
#if !LWIP_NETCONN_SEM_PER_THREAD
	sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
#endif /* !LWIP_NETCONN_SEM_PER_THREAD */

#if LWIP_MPU_COMPATIBLE
	*addr = msg->addr;
	err = msg->err;
#endif /* LWIP_MPU_COMPATIBLE */

	API_VAR_FREE(MEMP_DNS_API_MSG, msg);
	return err;
}
#endif /* LWIP_DNS*/

#if LWIP_NETCONN_SEM_PER_THREAD
void
netconn_thread_init(void)
{
	sys_sem_t* sem = LWIP_NETCONN_THREAD_SEM_GET();

	if((sem == NULL) || !sys_sem_valid(sem)) {
		/* call alloc only once */
		LWIP_NETCONN_THREAD_SEM_ALLOC();
		LWIP_ASSERT("LWIP_NETCONN_THREAD_SEM_ALLOC() failed", sys_sem_valid(LWIP_NETCONN_THREAD_SEM_GET()));
	}
}

void
netconn_thread_cleanup(void)
{
	sys_sem_t* sem = LWIP_NETCONN_THREAD_SEM_GET();

	if((sem != NULL) && sys_sem_valid(sem)) {
		/* call free only once */
		LWIP_NETCONN_THREAD_SEM_FREE();
	}
}
#endif /* LWIP_NETCONN_SEM_PER_THREAD */

#endif /* LWIP_NETCONN */
